CN103616646A

CN103616646A - Method for correcting SOC through OCV-SOC curve

Info

Publication number: CN103616646A
Application number: CN201310630382.1A
Authority: CN
Inventors: 刘飞; 文锋; 阮旭松; 徐志深
Original assignee: Huizhou Epower Electronics Co Ltd
Current assignee: Huizhou Epower Electronics Co Ltd
Priority date: 2013-12-02
Filing date: 2013-12-02
Publication date: 2014-03-05
Anticipated expiration: 2033-12-02
Also published as: CN103616646B

Abstract

The invention relates to a method for correcting an SOC through an OCV-SOC curve. The method comprises the steps that firstly, powering on is conducted and the battery standing time T is detected; whether the battery standing time T exceeds a preset threshold value or not is judged; if yes, the next step is executed; the minimum monomer voltage cellv_min of a battery and the current SOC value are obtained; at least three feature points Pn and corresponding appropriate lower SOC values SOCn are set on a relatively flat section on the OCV-SOC curve; the minimum monomer voltage cellv_min of the battery and the voltage value cellv_n of each feature point are compared and judged and the SOC values are corrected. Compared with the prior art, the method for correcting the SOC through the OCV-SOC curve has the advantages that the SOC correcting chance is increased, the SOC estimation precision is improved, the SOC values can be corrected to be within a section with values tending to a reasonable value, and the situation that the initial SOC value is not right or the SOC declines due to self discharge of the battery caused by long-time standing can be effectively dealt with.

Description

A kind of method of utilizing OCV-SOC curve correction SOC

Technical field

The present invention relates to the method for SOC of correction a kind of, specifically a kind of method of utilizing OCV-SOC curve correction SOC.

Background technology

Electric automobile requires battery management system that SOC value is accurately provided in real time, and battery SOC estimation is the Focal point and difficult point of battery management system.In actual applications, the SOC of ferric phosphate lithium cell estimates that conventional method has simple and effective open-circuit voltage method and ampere-hour integral method.Open-circuit voltage method needs the sufficiently long time of battery standing, and simultaneously battery SOC is obvious with open circuit voltage variations, when battery management system works on power according to the initial SOC value of monomer voltage estimating battery.Ferric phosphate lithium cell conventionally utilizes between the low side of its OCV-SOC curve and high-end linear zone and carries out SOC estimation.Ampere-hour integral method is current most widely used the most simple general evaluation method.In the course of work of battery, the charging and discharging currents of battery is carried out to integral operation to the time, then the dynamic SOC value of estimating battery.Ampere-hour integral method is higher to current sample accuracy requirement, otherwise may produce larger cumulative errors after long-play.Also there is the method that adopts open-circuit voltage method and ampere-hour integral method to combine.Larger by the SOC error of ampere-hour score accumulation after battery long-play, need to utilize the open-circuit voltage correction SOC after battery sufficient standing.Ferric phosphate lithium cell is interval owing to having longer charge and discharge platform, after battery sufficient standing, if monomer voltage in platform interval range, cannot carry out SOC accurately, revises.Particularly ferric phosphate lithium cell is applied to the situation of motor vehicle driven by mixed power, the SOC of motor vehicle driven by mixed power battery is used between the platform area of interval and ferric phosphate lithium cell and substantially overlaps, after motor vehicle driven by mixed power long-play, the SOC error of accumulative total, by increasing, cannot meet vehicle application actual demand.

The present invention proposes a kind of method of utilizing ferric phosphate lithium cell OCV-SOC curvilinear characteristic point to carry out SOC correction.On the basis of open-circuit voltage method and ampere-hour integral method, improve the estimation precision of ferric phosphate lithium cell SOC between platform area.

Summary of the invention

For above-mentioned prior art, the technical problem to be solved in the present invention is: the method for the OCV-SOC of utilization curve correction SOC a kind of is provided, has increased the meeting of SOC straightener, improved SOC estimation precision, SOC value is adapted in an interval that is tending towards reasonable value.

In order to address the above problem, the method for the OCV-SOC of utilization curve correction SOC of the present invention is

S1: start detects battery standing time T;

S2: judge whether battery standing time T surpasses pre-set limit; If surpass, carry out next step operation; If do not surpass, be back to S1;

S3: obtain the minimum monomer voltage cellv_min of battery and current SOC value;

S4: at least three unique point Pn and corresponding and suitable SOC value SOCn on the low side are set on the comparatively mild interval of OCV-SOC curve;

S5: the relatively judgement of the magnitude of voltage cellv_n of the minimum monomer voltage cellv_min of battery and each unique point and the correction of SOC value.

Preferably, the relatively judgement of the magnitude of voltage cellv_n of the minimum monomer voltage cellv_min of described battery and each unique point with the correction step of SOC value is:

If the minimum monomer voltage cellv_min of battery is greater than magnitude of voltage cellv_n and the former SOC value of unique point and is less than SOC value corresponding to this unique point, revised SOC value is the SOCn corresponding with unique point Pn;

If the minimum monomer voltage cellv_min of battery is less than magnitude of voltage cellv_n and the former SOC value of unique point and is greater than SOC value corresponding to this unique point, revised SOC value is the SOCn corresponding with unique point Pn;

If other situations, former SOC value is constant.

Preferably, described SOCn considers after monomer voltage measuring error 10mv and the poor problem of battery consistency, the value after the processing suitable on the low side that SOC value corresponding to unique point Pn made.

Compared with prior art, the advantage that the present invention has is: increased the meeting of SOC straightener, improved SOC estimation precision, SOC value can be adapted in an interval that is tending towards reasonable value, can successfully manage SOC initial value not to or battery due to the long-term standing situation that causes SOC that self discharge causes to decline.

Accompanying drawing explanation

Fig. 1 is the method flow diagram that utilizes OCV-SOC curve correction SOC of the invention process.

Fig. 2 is the relatively judgement of magnitude of voltage and the modification method process flow diagram of SOC value of the minimum monomer voltage of battery and each unique point in Fig. 1.

Fig. 3 is OCV-SOC curve map.

Terminological interpretation: OCV is open-circuit voltage; SOC is state-of-charge.

embodiment

In order to allow those skilled in the art understand better technical scheme of the present invention, below in conjunction with accompanying drawing, the present invention is further elaborated.

The specific embodiment of the present invention as shown in Fig. 1～Fig. 2, a kind of method of utilizing OCV-SOC curve correction SOC, the method is

S1: start detects battery standing time T.

S2: judge whether battery standing time T surpasses pre-set limit; If surpass, carry out next step operation; If do not surpass, be back to S1.

S3: obtain the minimum monomer voltage cellv_min of battery and current SOC value.

S4: at least three unique point Pn and corresponding and suitable SOC value SOCn on the low side are set on the comparatively mild interval of OCV-SOC curve.

OCV-SOC curve as shown in Figure 3, the OCV-SOC curve of the phosphoric acid iron lithium battery that this curve is certain manufacturer production.

The setting of unique point Pn is to draw according to comprehensive analysis of the OCV-SOC curvilinear characteristic of ferric phosphate lithium cell.Make a concrete analysis of as follows:

In Fig. 2 on the comparatively mild interval of curve, the obvious of short duration rising at SOC=65% place, this curve of naming a person for a particular job be divided into rise before platform, rising point and rising rear platform three parts.In Fig. 2, be provided with five unique point P1～P5, wherein, P1, P2 are two endpoint values of platform before rising, and P3 is rising point, and P4, P5 are two endpoint values of rising rear platform.

Being set to of SOCn considered after monomer voltage measuring error 10mv and the poor problem of battery consistency, the value after the processing suitable on the low side that SOC value corresponding to unique point Pn made.

As shown in Table 1, the particular location of each unique point as shown in Figure 3 for concrete unique point Pn and corresponding SOCn.

The mapping table of table one unique point Pn and SOCn

S5: the relatively judgement of the magnitude of voltage cellv_n of the minimum monomer voltage cellv_min of battery and each unique point and the correction of SOC value; Idiographic flow as shown in Figure 2.

If other situations, former SOC value is constant.

For example, when the minimum monomer voltage cellv_min of battery is 3.3V, SOC value of battery should be greater than 60% under normal circumstances.

Cellv_min=3.3V>cellv_1=3.286V, if former SOC value is less than 35%, revising SOC value is 30%, constant if former SOC value is greater than 35%, SOC value;

Cellv_min=3.3V>cellv_2=3.296V, if former SOC value is less than 60%, revising SOC value is 35%, constant if former SOC value is greater than 60%, SOC value;

Cellv_min=3.3V<cellv_1=3.314V, if former SOC value is greater than 65%, revising SOC value is 60%, constant if former SOC value is less than 65%, SOC value;

Cellv_min=3.3V<cellv_1=3.33V, if former SOC value is greater than 70%, revising SOC value is 65%, constant if former SOC value is less than 70%, SOC value;

Cellv_min=3.3V<cellv_1=3.338V, if former SOC value is greater than 95%, revising SOC value is 70%, constant if former SOC value is less than 95%, SOC value.

Method simple practical provided by the invention, conventionally and open-circuit voltage method and ampere-hour integral method use simultaneously.Particularly the situation of the standing rear monomer voltage of ferric phosphate lithium cell between platform area, can be controlled at SOC within the scope of a concrete reasonable interval.

The above is preferred embodiments of the present invention, not the present invention is done to any pro forma restriction.It should be noted that; in the situation that not deviating from spirit of the present invention and essence thereof; those of ordinary skill in the art are when making according to the present invention various corresponding changes and distortion, but these changes and distortion all should belong to the protection domain of the appended claim of the present invention.

Claims

1. a method of utilizing OCV-SOC curve correction SOC, is characterized in that: the method is

S1: start detects battery standing time T;

2. the method for utilizing OCV-SOC curve correction SOC according to claim 1, is characterized in that, relatively judgement and the correction step of SOC value of the magnitude of voltage cellv_n of the minimum monomer voltage cellv_min of described battery and each unique point are:

If other situations, former SOC value is constant.

3. the method for utilizing OCV-SOC curve correction SOC according to claim 1, it is characterized in that, described SOCn considers after monomer voltage measuring error 10mv and the poor problem of battery consistency, the value after the processing suitable on the low side that SOC value corresponding to unique point Pn made.